If you thought the component manufacturing stage of your Gradient’s journey was exciting, then buckle up. 

This week we’ll learn about the phase the Earth loves the most: Assembly of your Gradient’s mighty heat pump, charged with planet-friendlier refrigerant. 

What's in a heat pump?

Your heat pump consists of a compressor, heat exchanger, expansion valve, and a reversing valve – that’s what enables your system to both heat and cool. 

An innovative step we've taken is to include a second heat exchanger that helps to transfer heat in or out of your home depending on your seasonal needs for warmer or cooler air. 

All of these parts are permanently connected together with copper tubes.

So how do you build a heat pump?

One of our team members who specializes in this work is Kim, our Senior Prototyping Technician. She’s responsible for our most technical heat pump work, like building entire prototype systems from scratch using methods like brazing.

Brazing involves joining together pieces of metal by melting and flowing a filler metal into a joint. That’s what makes it different from welding, where you melt the base metal of each workpiece together.

Here you can see Kim brazing a pressure sensor onto a heat pump part. The pressure sensor is wrapped in a wet cloth to keep sensitive components cool while brazing – very important, since understanding the system’s pressure is critical to optimizing your heat pump’s performance.

Note: This image was taken for a photoshoot. We always follow proper safety precautions while working.

A strong brazed joint requires a clean copper tube with a good fit to the mating parts. Cutting the tube leaves a rough edge on the inside of the cut tube. Below, Kim uses a deburring tool to remove the excess material and prepare the copper tube for brazing. 

At this stage we’d be remiss not to show you a cool pic of Steve, our Engineering Lab Director, firing up an oxy acetylene torch (below).

Sure, looks like he’s just having fun – and let’s be clear: he is – but he’s actually beginning to dial in the torch flame for brazing. 

As Steve dials in more oxygen, the flame becomes smaller and takes on a beautiful bright blue hue. 

After your heat pump is brazed together, it’s tested for leaks and the air is removed from the system. Next, your heat pump is charged with planet-friendlier R32 refrigerant and hermetically sealed. 

Hold on: refrigerant? Do I need an expert to install a Gradient heat pump?

If you researched other heat pump options, you likely know that charging a heat pump, i.e., adding refrigerant, usually happens at the time of install and requires a certified professional.

Due to the manual process of adding refrigeration there's also significant risk for human error, which often results in refrigerant leaks. Leakage has a serious environmental impact. In fact, it’s a large contributor of greenhouse gas emissions.

But because your factory-sealed Gradient will come charged with planet-friendlier refrigerant, there’s no need to hire a professional.

What comes next?

Now that you've seen how your system's parts are fabricated and how its heat pump is built and charged, we're ready for the next phase – putting all those parts together!

Stay tuned for our next update, where you’ll get a glimpse into our assembly line and our patented secondary coolant loop. 

Cheers to a cooler world,

The Gradient Team